Smoke luminous or other visible trails from aircraft



Jam 4, 1927., 1,613,134

J. c, SAVAGE SMOKE LUMINOUS OR OTHER VISIBLE TRAILS FROM AIRCRAFT Filed June 50, 1922 2 Sheets-Sheet l Jan. 4, 1921. 1;613,l34

J. c. SAVAGE SMOKE] LUMINOUS OR OTHER VISIBLE TRAILS FROM AIRCRAFT Filed June 50 1922 2 Sheets-Sheet 2 VFILVE VfiLl J a: a? 9 um vs um. vs

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Patented Jan. 4,1927,

UNITED STATES PATENT OFFICE. I

JOHN CLIFFORD SAVAGE, OF RYDE, ISLE OF'WIGHT, ENGLAND, ASSIGNOR TO THE SKYWRITING CORPORATION OF AMERICA.

SMOKE LUMINOUS OR OTHER VISIBLE TRAILS FROM AIRCRAFT.

Application filed J'une 30, 1922,'Seria1 No. 571,938, and in Great Britain August 12, 1921.

This invention relates to the formation of smoke, luminous or other visible trails from aircraft for signalling, advertising 01' other purposes and its main object is to provide means whereby intermittent, trails such as those required for making characters or letters may be rendered definite and clear cut and free from any residual trail which con-' tinues after the valve controlling the smoke production is closed.

Ina system where a simple or complex fluid is injected into the exhaust of an aircraft motor intermittently by the use of a valve or valves in the fluid supplying system, the chief objection lies in the time lag that occurs, when commencing the smoke or visible trail, between the opening of the valve and the commencement of the smoke or visible trail on the one hand, and, when terminating the smoke or visible trail, between the closing of the valve and the termination of the smoke or visible trail on the other hand.

Especially is difliculty encountered in terminating the intermittent smoke or visible trail after the valve supplying the fluid is closed, because some of the fluid remains upon the walls of the exhaust passage and a visible trail continues to be emitted long after the valve is closed, thus confusing the signals being formed.

According to one feature of the present invention I employ means, such as a valve, adapted to direct the exhaust gases fromthe engine at will either direct into the atmosphere that is to say without being rendered visible or into a region wherethey are Tendered visible before escaping free.

By the use of what I may term an-exhaust directing valve as above described, not only is an improvement effected in systems where the smoke producing fluids are injected into or otherwise mixed with the exhaust-but it gives rise to another system of smoke or vis- As regards the controls for such sy tems as are hereinbefore described there may be employed either a single hand lever controlling and operating both the directing valve and the valve (when used) controlling the emission of the smoke producing substance at one and the'same time or these two valves can be operated separately.

In order that the invention may be clearly understood and readily carried into efiect, I will now describe the same more fully with reference to the accompanying drawings in which Figure 1 illustrates diagrammatically one arrangement for operating in accordance with my invention. 1

Figure 2 illustrates a modified arrangement.

Figures 3, 4 and 5 diagrammatically illustrate means for directing the exhausfigases to any one of a series of chambers for.- reaction with visualizing material. 1

Referring first more particularly t0 th eof the engine exhaust pipe is represented by the part marked 1, and 2 indicates the exhaust directing valve therein. This valve is represented diagrammatically as pivoted at 3 and rocked by an external arm 4 connected to an operating rod 5. The rod 5 is also connected by a link 6 with a valve 7 controlling the supply of trail producin material to the jets 8 which project into t e pipe 1. Alternatively the jets might project into a jacket located within or around the pipe 1. From the foregoing description and the accompanying drawing it will be understood that when the parts are in the position illustrated the exhaust gases from the engine are diverted from the exhaust pipe 1 along the branch pipe 9 direct into the atmosphere but when the rod 5 is drawn to move the valve.2 into its alternative position the exhaust gases pass straight along the pipe 1 and past the jets 8.' In the particular construction shewn the operation of the valve 2 erated if desired. Moreover the jets 8 may if desired be independently supplied and controlled.

If desirable the valve 2 (hereinafter called the exhaust directing valve) may be so made as for example by being perforated that even when the exhaust gases are being released direct into the atmosphere, 9. regulatable portion of these gases may be admitted into the smoke producing region, this being particularly useful in a system in which such region is a portion of the exhaust channel as it serves to maintain the temperature of this smoke channel at the point which will enable the full smoke efi'ect to be produced as soon as the exhaust directing valve is opened. In the case of a perforated valve means may be provided to vary the number of holes in action.

In the arrangement illustrated in Figure 2 the smoke producing material is not introduced into the escaping stream of exhaust gases but the latter are introduced into said material thereby combinin the material reservoir and the smoke pro ucing means into a single construction. In the particular construction illustrated the exhaust pipe 1 terminates in .a nest of jets 11 in a chamber 12 in which smoke producing material is placed toa depth sufiicient to submerge the jets, so that when the exhaust gases issue from the jets theybubble through the smoke producing material and give rise to the formation of smoke. This smoke then passes through the end chamber 13 and through the exit pipe 14 which may contain bafiies 15. A jet 16 may be'provided to introduce any additional material to mingle or react with the mixture or exhaust gases and vaporized smoke producing material or their reaction products. This method of smoke production is essentially due to the directing valve and branch pipe arrangement since the latter enables the production of smoke to be started and stopped at any instant without interfering with the continuous nature of the stream of exhaust gases.

The feature of the fundamental novelty and importance common to both of the constructions above described is the elimination of the time lag hereinbefore referred to and the consequent production of clear sharply defined trail elements or signals.

Although I have referred always in the above description to exhaust gases the stream or current of gases employed may in some cases consist of or be supplemented by the air stream surrounding the aircraft such airstream being suitably caught confined and directed as by a chute and conduit attached to the aircraft frame. In such a case the directing valve is operated at will to permit the airstream to flow through the conduit unaffected or to pass into contact with or over or through one or more substances .which singly or collectively impart visibility to the air. This airstream may if desired be heated by the engine to more readily take up the visualizing substance or substances.

Also although the directing valve as above described is constructed or arranged to control only one approach passage and two alternatively closed departure passages, a valve or valves controlling more passages or channels may be employed. They may for example control separate smoke channels in each of which the chemicals necessary to produce (liil'erent coloured smokes may be stored or introduced. For example a distributing valve or system of valves may control the flow of exhaust gases to any one or more selected chambers of a series of chambers such as 12 in Figure 2 each chamber containing material for producing smoke of a different kind or colour from that of the others. Such a system is illustrated in Figures 3, 4- and In the said F igurcs, 1 represents the exhaust pipe and 9* a branch passage leading therefrom adapted to deflect the exhaust gases directly L1 into the atmosphere when a deflecting valve 17 is in proper position therefor. Two chambers A and B are provided to receive the visualizing material, and 18 is a deflecting valve for deflecting the exhaust gases either into chamber A or chamber B. 19 is a control rod for simultaneously operating deflecting valve 18 and also valves B and A in the chemical pipe lipes 20 and 21, the first line terminating in nozzle 2O in chamber A and the second terminating in nozzle 21 in chamber B. 22 is an operating rod for simultaneously controlling exhaust dcflecting valve 17 and chemical line valves B and A In the operation of the device, it may be considered for the purposes of illustration that chamber A is intended for generating blue smoke and chamber B red smoke. If no smoke is required, the operating rods 19 and 22 are moved to the position illustrated in Figure 5, exhaust deflecting valve 17 being so positioned that the exhaust gases are permitted to escape directly into the atmosphere through branch passage. 9", and chemical valves B A and A will be closed thus preventing the .introduction of any smoke producing chemicals into the chambers A and B. If blue smoke is required, the operating rods are placed in position shown in Figure 3, so that the engine exhaust gases are delivered to chamber A, chemical valves B and B being open and valve A in chemical line 21 closed. If red smoke is required, the operating rods are placed in the position illustrated in Figure 4, valve 18 closing chamber A from the exhaust! gases, the latter being directed into chamber B. the required movement of operating rod 19 to effect this result automatically closing valve B and opening valve A If intermittent blue smoke is required, operating rod 19 may be left in its position shown in Figure 3 and operating rod 22 manipulated to alternately deflect the exhaust gases into 'a branch pipe 9* and back into chamber A; If intermlttent red smoke is desired, controlling rod 19 is left in its position. as shown in Figure 4 and controlling rod 22 is manipulated to alternately defleet the exhaust gases through branch pipe 9 and back into chamber B.

It is to be understood that the drawings merely illustrate somewhat diagrammatical-- ly the essential features of my invention and that in practice various constructional details would be resorted to. For example the entire piping and smoke producing chambers maybe lagged if necessary or re-' fractory material may be packed in the smoke producing region of the piping. Also to assist in the rapid and complete reaction between certain material it may be necessary or advisable 'to provide a catalytic agent and this may in the case for example 0 apparatus such as shewn in Figure 2,

be contained in a sump 17 at the base of the end chamber 13.

What I claim is:

1. In the production of smoke or other visible trails from aircraft for aerial advertising or other purposes a pipe a branch passage on said pipe a valve in said pipe means for operating said valve whereby fluid enterin said ipe is caused to pass through sai branc passage or through said pipe and a plurality of separate devices for rendering the fluid passing through said pipe visible. y

2. In the productionof smoke or other visible trails from aircraft for aerial advertising or other purposes an exhaust pipe a branc passage on said pipe a valve in said pipe means for operating said valve whereby gases enterin said pipe are caused to pass through sai branch passage or through said pipe a plurality of separate devices beyond the branch passage for-rendering the gases passing through said pipe visible and means for directing the gases to anyselected device or devices at will.

J. C. SAVAGE. 

